Cutting fluid - yes/no``

Hello all, Now that workshop in in the final stretch on completion I need to decide on this matter. What's the consensus on using cutting oil/suds for normal model engineering use? Soluble or neat? Have read somewhere that for ME use, none is required due to the fact that we don't generate the heat compared with industry, due to lighter machines. Although I had a suds pump plumbed to lathe and mill 20 years ago, I hardly ever used it. Just squirted onto the work using oil can, or drip feeder. Cannot say I noticed any difference in finish. Emco V10P and FB2 mill. Comments please. Regards

GeoffH (The Pirate) Norfolk - UK not VA

Reply to
Loading thread data ...


For the vast majority of work I don't use soluble oil - the exceptions are parting off, some threading and fine finishing.


Reply to
Andrew Mawson

I use a very small jar of 10 percent mix soluble, and a brush on my lathe at home. Lasts a long time, mainly because it gets used only when I find I am not getting a finish that I want, usually on low carbon steel, usually when threading.

A bit of creativity with some cut up soda bottles and a couple decently strong magnets, and you can build a spray sheild that will work better than any I have seen available. Usually the commercial ones do not do much of a job stopping the coolant from spraying dowm ones left leg.

All our machines at work are coolant equipped. sometimes it's used, other times not. Nice to have the option.

I have not used neat oil, but have read others stating that there were fewer issues in the long term, as the stuff did not go rancid or otherwise go "animal", and did not freeze, though it got thick in the cold shops.

Cheers Trevor Jones

Reply to
Trevor Jones

Hopefully JS will chip in here, he posted something on one of the US forums earlier this year about neat cutting oil that gave a superb finish. However as you probably know John is an industrial user rather than a hobbyist and does things on his big lathes that would make some of our little Myfords and the like run and hide in the corner

I tend to use suds from a squeezy bottle on the mill more than the lathe, occasionally I use a drop or two of Rocol RTD when turning, and though this probably isn't the best it can sometimes help the finish.

For cutting Aluminium, whether on lathe or mill, absolutely the best cutting fluid I can recommend is pure isopropyl alcohol. I have a special swan-necked squeeze bottle designed for this and squirt a bit on whenever I have to cut ally. It gives a superb finish and evaporates off with the aid of a quick wipe when done - forget that WD40 stuff which leaves a nasty messy residue.


Reply to
Peter Neill

I think it all depends what you're doing. I do a lot of turning dry with carbide tools, but wouldn't be without some sort of cutting fluid for stainless or silver steel, EN8 or anything more exotic than that, also for threading. Rocol RTD is pretty good for threading, but it can get expensive if you start to use it more generally. On my mill which is still waiting for a new coolant pump, I use a spray head on a plastic bottle (think greenhouse insecticide sprays) with neat cutting oil. It has the benefit of being less messy than full coolant. I have neat oil in my drilling machine, simply because it (the cutting fluid) gets used so little that it probably would go rancid. The snag with it is that parts have to be cleaned afterwards, whereas soluble oil generally runs off leaving only a very thin coating.


Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service

Reply to
Tim Leech

For model engineering lathe, mill and drill use neat cutting oil applied with a small brush although most times they can all be worked dry. Its all down to finish and tool sharpness. An advantage on soft materials is that cutting oil will generally avoid the chips sticking to the tool cutting edge. Soluble oil tends to tarnish machine beds and chucks I have found and some ordinary oils too probably due to something in their content.......

Cutting oil when taking heavy cuts generating a lot of heat will vaporise and stink the workshop out. Its not too unpleasant a smell but if it gets into the house watch out for management complaining. One advantage of a remote workshop at the bottom of the garden! Mine adjoins the house and it will pervade into the domestic space which gives me ear ache!


Reply to
Alan Marshall

Like most thinks there are pro's and cons.

Upside of suds is. it's cheap, works well and handy to apply. Being water based it removes heat readily. Downside is it can go rancid although whatever lives in the bottom of my big lathe's tank scares the shit out the H&S guy. Another down side is that it marks the bed under the vise if not removed off and cleaned. Same applies for cross slides.

Upside of neat coolant is no marking, lubricates the parts other beers can't reach and good surface finish, especially on threading.

Down side is it's neat oil and doesn't get rid of heat like water based. Industry copes with this by flood cooling inside enclosed machines.

Small machines don't really have this problem as they don't have the horsepower to burn this oil up. Cut off point seems to be about 6" centre height. I have oil in the CVA and as it's limited to MT2 I can 'just' get away with it. A 7/8" drill can start smoking a fair bit if pushed. I gave a drum away to a friend in industry who had a 8" Colchester and he had to swap it back to suds due to fumes. So far I have the gear hobber, CVA lathe, power saw and pipe cutter on oil, the rest are still on suds as they tend to work heavier.

I get this oil from a place that sells new Swiss lathes, they fill the machine up, demo it to a customer, then drain it and get rid. Most times it's never done a weeks work. I buy it in bulk, 80 to 100 gallons at a time and use some and sell some on. It's great for manual work in oil cans, bench work for tapping etc and dribbling on for parting off etc.

I'm prepared to let this go very cheap to list readers BUT it will have to be collect only, Junction 24/25 M1 area as I can't be arsed to ship this.

-- Regards,

John Stevenson Nottingham, England.

Visit the new Model Engineering adverts page at:-

formatting link

Reply to
John Stevenson

For "home" use, I use "Millicut 20" from millers oils, (Brighouse also Leicestet) as a general purpose neat cutting oil with good results. Originally spent ages rigging up a suds pump on my larger lathe, only to never need it, and I seem to do more stainless than anything else. Beware of corrosion(of your precious machines) & separation problems on any water-based cutting fluids if they are not to be used pretty much every day, and mixed correctly. Also all sorts of yeasts and other yuk breed in "suds" tanks, especially when not used. With my health and safety hat on, and because I have not seen this mentioned for a while, a reminder ( to all ): Mineral oil can cause skin and other cancers ( particularly testicular ! ), loads of suds splashing about a production machine shop is a vision from 20+ yrs ago and rightly so. The majority of soluble cutting oils, even "synthetic" are mineral oils, and having a large volume pumping around only makes it more likely that you will get splashed, or worse, end up saturating overalls that are worn repeatedly, and indeed swallowing some of it! In short, I'd use neat oils for cutting on modelling projects. Mark G.

Reply to
Mark G

Thanks for all the replies. Think I will go dry and just use neat oil for finishing, drilling and reaming, and the occasional use of soluble via a spray bottle or suchlike. Will keep the group informed as to how things go. Cheers

GeoffH (The Pirate) Norfolk - UK not VA

Reply to

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.